1. Field of the Invention
This invention relates to an image display apparatus.
2. Description of the Related Art
In the past, as an example of a television receiver and a display device for receiving a television signal, a display signal from a computer and so on and for carrying out image display, by use of a plurality of electron-emitting devices which were interconnected as a matrix wiring and a display panel which is configured by a fluorescent screen for emitting light when it received electron irradiation thereof, such structures as in Patent Document 1 (JP-A-6-342636 gazette) and Patent Document 2(JP-A-8-212944 gazette) have been known.
An image display apparatus which was described in these documents is configured such that a plurality of surface conduction electron-emitting devices are connected in a matrix shape by use of a plurality of scanning wirings and a plurality of modulation wirings.
And, image display of one frame is realized, by applying a selection electric potential to one scanning wiring and applying a drive electric potential to respective plural modulation wirings, by driving the electron-emitting device with an electric potential difference (hereinafter, referred to as a drive voltage) of the selection electric potential and the drive electric potential so as to carry out display of 1 line portion, and further, by sequentially switching the scanning wiring to be selected by a predetermined scanning frequency so as to carry out scanning in a vertical direction.
Now, in an image display apparatus which was described in Patent Document 1, as shown in FIG. 6, image display of one frame is carried out. Here, in order to make an explanation easy, pixels of a display panel are connected by matrix wirings of 8 column×6 rows, and one frame period is, as described later, divided into eight scanning periods, so as to carry out image display.
That is, as shown in FIG. 6, luminance data for determining an amount of light emission with respect to each pixel divides one frame period into eight scanning periods, and with respect to each scanning period, data for one scanning is sent in a manner of pixel interleave. In passing, a panel is of six rows, but there are frame image signals for seven rows, and a seventh image signal is made to be of non-display.
This luminance data is held by a modulation wiring drive circuit which was provided with respect to each modulation wiring, and outputs a voltage pulse having an effective electric potential in proportion to size of luminance data, with respect to each scanning period, and with respect to each modulation wiring, for driving the modulation wiring. Also, here, as to selection scanning of scanning wirings, the scanning will be carried out as follows.
That is, a first scanning period is assigned to a non-display period, and no selection electric potential is given to any scanning. In a second scanning period, the selection electric potential is given to a first row scanning wiring, and an opportunity of light emission is given to a pixel for first scanning. In a third scanning period, the selection electric potential is given to a second row scanning wiring, and the opportunity of light emission is given to a pixel for second scanning. In a fourth scanning period, the selection electric potential is given to a third row scanning wiring, and the opportunity of light emission is given to a pixel for third scanning. In a fifth scanning period, the selection electric potential is given to a fourth row scanning wiring, and the opportunity of light emission is given to a pixel for fourth scanning. In a sixth scanning period, the selection electric potential is given to a fifth row scanning wiring, and the opportunity of light emission is given to a pixel for fifth scanning. In a seventh scanning period, the selection electric potential is given to a sixth row scanning wiring, and the opportunity of light emission is given to a pixel for sixth scanning. An eighth scanning period is assigned to a non-display period, and no selection electric potential is given to any scanning.
Also, a technology which was described in Patent Document 2 is such a technology that a display panel comprising a plurality of electron-emitting devices which was interconnected as a matrix wiring is divided into two above and below, and, independently for one for an upper half area and one for a lower half area, a modulation wiring modulation circuit and a scanning wiring selection circuit are provided.
According to this technology, it becomes possible to expand scanning selection time two times, and a luminance margin due to this is parted to drive current reduction, so that it is possible to reduce luminance lowering due to voltage drop which is generated by a drive current flowing through the scanning wiring.
Also, such a structure as described in Patent Document 3 (JP-A-2000-250473) has been known. A technology which was described in this Patent Document 3 is one for carrying out high frame rate driving for improving light emission efficiency of a fluorescent material. This technology will be described with reference to FIG. 7. In passing, in order to make understanding easy, pixels of a display panel 100 are connected by matrix wirings of 8 columns×6 rows.
That is, as shown in FIG. 7, the technology which was disclosed in Patent Document 3 is such a drive display method that, when received is an image signal which corresponds to six scanning lines in one frame period (60 Hz) as an input signal, one frame period is divided into two sub-frame periods (120 Hz), and display is carried out twice repeatedly in a half display period. By this, since it is possible to shorten time for exciting the fluorescent material consecutively, it becomes possible to improve light emission efficiency. In passing, such a structure as described in Patent Document 4(JP-A-8-50462 gazette) has been known.
Also, in recent years, a television signal format has been diversified. For example, in BS digital broadcasting, an operation with a diversified range of formats is carried out. On one hand, in resolution of a display panel at the side of an image display apparatus for receiving suchlike broadcasting, various combinations are conceivable.
That is, in case of receiving a TV signal which was based upon a high resolution format, by use of a panel with the number of pixels which is in conformity with broadcasting with low resolution, there is a method for carrying out image display in which resolution conversion is carried out so as to be in conformity with the number of pixels of a low resolution panel.
On the other hand, in case of receiving a TV signal of a low resolution format, by use of a panel with the number of pixels which is in conformity with broadcasting with high resolution, there is a method for carrying out image display in which resolution conversion is carried out so as to be in conformity with high resolution.